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Objective The primary focus of this example is to demonstrate the use of Appendix A and Appendix B for a two-span continuous structure

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Appendix A Overview Accounts for the ability of compact and non-compact sections to resist moments greater than M y Economy gained by Appendix A provisions increases with decreasing web slenderness Effects of St. Venant torsion are incorporated

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Design Loads – WS and WL WS Wind forces are calculated assuming bridge is located 30’ above water in open country Wind on upper half of girder, deck, and barrier assumed to be resisted by diaphragm action of the deck WS = k/ft (on bottom flange) WL Assumed to be transmitted by diaphragm action WL is neglected

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Appendix B Requirements (cont.) Shear Section Transitions No section transitions are permitted within the first cross-frame spacing on each side of the pier Bearing Stiffeners Bearing stiffeners are required to meet projecting width, bearing resistance, and axial resistance requirements

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Redistribution Moment Amount of moment redistributed to positive bending region is a function of the effective plastic moment, M pe Higher M pe values are permitted for girders with either: Transverse stiffeners placed at D/2 or less on each side of the pier “Ultra-compact” webs such that Alternative M pe equations are given for strength and service limit states

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Concluding Comments Fatigue requirements significantly impact the design of the positive moment region due to the relatively high distribution factor for the exterior girder Constructibility and Appendix B requirements led to the use of a 15 ft cross-frame spacing throughout Use of Appendix A leads to increasing economy with decreasing web slenderness (that is a section with a noncompact web at the upper limit will gain very little from Appendix A) Appendix B provides even greater economy